Methods for repair of abnormal mitral valves

ABSTRACT

Methods of remodeling an abnormal mitral valve with an annuloplasty ring having a reduced anterior-to-posterior dimension to restore coaptation between the mitral leaflets in mitral valve insufficiency (IMVI). The ring has a generally oval shaped body with a major axis perpendicular to a minor axis. An anterior section lies between anteriolateral and posteriomedial trigones, while a posterior section defines the remaining ring body and is divided into P 1 , P 2 , and P 3  segments. The anterior-to-posterior dimension of the ring body is reduced from conventional rings; such as by providing, in atrial plan view, a pulled-in P 3  segment. The ring body may have a downwardly deflected portion in the posterior section. The downwardly deflected portion may have an apex which is the lowest elevation of the ring body and may be offset with respect to the center of the downwardly deflected portion toward the P 3  segment.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/094,145, filed Apr. 26, 2011, which is a continuation of U.S. patentapplication Ser. No. 10/882,031, filed Jun. 30, 2004, now U.S. Pat. No.7,935,145, which is a continuation of U.S. patent application Ser. No.10/678,338 filed Oct. 3, 2003, which is a continuation-in-part of U.S.patent application Ser. No. 10/192,516, filed Jul. 8, 2002, now U.S.Pat. No. 6,858,039, and which is also a continuation-in-part of U.S.patent application Ser. No. 10/144,932, filed May 15, 2002, now U.S.Pat. No. 6,726,717, which claims the benefit under 35 U.S.C. §119(a) ofItalian Application No. MI 2001A 001012, filed May 17, 2001, thedisclosures all of which are incorporated by reference in theirentireties.

FIELD OF THE INVENTION

The present invention relates generally to medical devices, specificallyto an annuloplasty ring and related procedure for surgicallyreconstructing the mitral valve annulus of a patient's heart. Morespecifically, this invention relates to a mitral valve annuloplasty ringand corresponding technique designed to correct an abnormal annulus inthe pathology encountered with all functional anomalies seen withischemic mitral valve insufficiency (IMVI), or other pathologiesresulting in functional mitral regurgitation.

BACKGROUND OF THE INVENTION

In the anatomy of the human heart, the left atrium receives oxygenatedblood from the lungs through the pulmonary veins. The mitral valveseparates the left atrium from the left ventricle. During diastole, asthe contraction triggered by the sinoatrial node progresses through theatria, oxygenated blood passes through the mitral valve into the leftventricle. In this phase, the aortic valve leading into the ascendingaorta closes, allowing the left ventricle to fill with blood. A similarflow of venous blood occurs from the right atrium through the tricuspidvalve to the right ventricle. Once the ventricles are full, theycontract during the systolic phase and pump blood out of the heart.During systole, the mitral valve closes and the aortic valve opens, thuspreventing blood from regurgitating into the left atrium and forcingblood into the aorta, and from there throughout the body. Because of thehigh pressures associated with the left ventricle during systole, properfunctioning of the mitral valve to prevent blood from flowing backthrough the system is extremely important.

The various anatomical components of a healthy mitral valve are depictedin FIG. 1. The mitral annulus MA comprises a fibrous ring encircling theorifice between the left atrium LA and the left ventricle LV. Theaverage cross-sectional area of the human mitral annulus is 4-10 cm².The mitral valve is a bicuspid valve having a posterior leaflet PL andan anterior leaflet AL. Chordae tendeneae CT (or simply “chordae”)extend from the free edges and the bases of the two leaflets to a pairof papillary muscles located in the LV. The two papillary muscles arelocated along the anteriolateral and the posteromedial wall of the LVand are therefore referred to as the anteriolateral papillary muscle APand the posteromedial papillary muscle PP, respectively.

Normal dilatation of the left ventricle and downward displacement of thepapillary muscles AP and PP pulls the chordae tendoneae CT, which inturn pull the leaflets open. When the ventricles contract the papillarymuscles are displaced upward, and the distance h between the papillarymuscles and the annulus is reduced. The chordae tendoneae become slack,allowing the leaflets to come together or “coapt.” As seen in FIG. 1,the leaflets coapt along a substantial surface area in the normalfunctioning heart, with the free edges of the leaflets mutually bendingtoward the left ventricle LV. For purpose of discussion, the mitralannulus MA of a normal, healthy heart lies generally in a datum plane 20defined perpendicular to the average blood flow direction 22 through themitral valve MV. Although a typical mitral annulus MA may bethree-dimensional, the datum plane 20 is representative of the relativepositions of the anterior and posterior side of the annulus.

In patients who suffer from a heart attack or cardiomyopathy, regions ofthe left ventricle lose their contractility and dilate. Dilation of theleft ventricle is often associated with a down and outward displacementof the papillary muscles. The change in the location of the papillarymuscles increases the distance between the papillary muscles and themitral valve leaflets. Since the chordae tendenae do not change theirlength significantly, the chordae tend to pull or “tether” the leaflets.In severe cases of left ventricle dilatation, the tethering of thechordae prevents the leaflets from coapting resulting in mitralregurgitation. Since this type of regurgitation is not associated withany disease or damage of the mitral apparatus it is often referred to as“functional” mitral regurgitation. Dilation of the left ventricle LV isalso a symptom associated with mitral regurgitation in patients withidiopathic dilated cardiomyopathy or ischemic cardiomyopathy, and inpatients with long-standing valvular regurgitation from other etiologiessuch as myxomatous disease, endocarditis, congenital defects, orrheumatic valvular disease.

As seen in FIG. 2, dilation of the left ventricle LV generally increasesthe distance h′ between the papillary muscles PM₁ and PM₂ and the mitralannulus MA. The increased distance h′ between the papillary muscles PM₁and PM₂ and the mitral annulus MA in turn increases the tension in thechordae tendoneae CT and may create a depression of the posterior aspectof the annulus below the datum plane 20, but this depression is notpronounced enough to reduce h′. The resulting increased tension in thechordae reduces the ability of the leaflets to come together duringsystole, which can lead to mitral valve insufficiency.

FIGS. 3 a-3 c illustrate the normal and abnormal mitral valve from theleft atrium as exposed during surgery, that is, in atrial plan view. Theanterior aspect of the mitral annulus MA forms a part of the “cardiacskeleton” and includes left and right fibrous trigones, LT and RT. Theleft trigone LT and right trigone RT are indicated at the junctionpoints of the anterior leaflet AL and posterior leaflet PL. Thesejunction points are also known as anteriolateral and posteriomedialtrigones or commissures between the leaflets. The posterior aspect ofthe mitral annulus MA, in contrast to the anterior aspect, consistsmainly of muscular tissue of the outer wall of the heart. The posteriorleaflet PL is divided into three scallops indicated as P1, P2, and P3 insequence from the left trigone LT counterclockwise to the right trigoneRT. FIG. 3 a shows the mitral valve and the papillary muscles of anormal mitral valve viewed from the left atrium. FIG. 3 b illustratesthe effect of an infarct of the posteromedial wall of the left ventricleLV on the geometry of the mitral apparatus, tending to cause anasymmetric dilation. The infarct causes the posteriomedial wall todilate moving the posteromedial papillary muscle PP outward. The chordaetendenae CT connected to the posteromedial papillary muscle PP pull thefree margins of the posterior leaflet PL and anterior leaflet AL awayfrom the natural line of coaptation. A gap is created between theleaflets along the P2-P3 region of the posterior leaflet PL. Asymmetricdilatation of the left ventricle LV associated with a regurgitating jetin the P2-P3 region is most common in patients with ischemic mitralregurgitation. In contrast, FIG. 3 c illustrates functional mitralregurgitation in the case of symmetrical dilatation of the LV. Bothpapillary muscles AP and PP move outward, stretching and pulling thewhole posterior leaflet PL outward. Symmetrical dilatation of the LV isassociated with dilatation of the posterior segment of the mitralannulus and a central regurgitant jet along the P2 region of the PL.Symmetrical dilatation of the LV is most common in patients withcardiomyopathy.

Mitral valve insufficiency is common treated by repairing or replacingthe mitral valve. The most widely accepted technique for mitral valverepair is the remodeling of the mitral annulus with an annuloplasty. Thegoal of the annuloplasty is two-fold: reduction of the annular area toits normal size and reshaping of the annulus to re-establish the normalgeometry of a health mitral annulus. In case of functional mitralregurgitation, the root cause of the insufficiency is the dilation ofthe LV and the associated dislocation of the papillary muscle. Thepurpose of the annuloplasty is to compensate for the dilation of the LVby reducing the cross-sectional area beyond its natural size. Thedownsized annulus brings the two leaflets closer togetherre-establishing coaptation of the leaflets.

Prostheses for annuloplasty surgery available on the market aregenerally of two types, with some hybrids. Flexible annular prostheses,made of various materials, that allow a “linear” reduction of theannular circumference, and rigid and semi-rigid annular prostheses madeof various materials, that allow the “linear” reduction of the annularcircumference and a geometric remodelling so as to re-establish thephysiological systolic shape of the annulus. Additionally, semi-rigidprostheses permit some deformation in order to allow the prosthesis tofollow the deformations of the annulus-during the cardiac stages. Allthe rigid and semi-rigid annular prostheses have a kidney-like orcoupled D shape, with an anterior half-ring, rectilinear in firstapproximation that gets sutured in correspondence with the anteriorvalve leaflet and a curved posterior half-ring that is sutured incorrespondence with the posterior valve leaflet. The shape of theannular prostheses at issue reproduces the configuration of the valveannulus during the ventricular systole, and therefore in the stage ofthe valve closing. The ratio between minor axis and major axis isapproximately 3:4 in all the models currently on the market since itreproduces normal anatomical ratios.

The “downsizing” technique involves, for example, selecting a 26 mm ringfor a nominal 28 mm annulus, while still maintaining the minoraxis/major axis size ratio of approximately 3:4. The size nomenclaturerefers to the width of the major axis. Although good results have beenreported with the downsizing technique, the reliability and durabilityof this operation to correct ischemic mitral valve insufficiency are notas good as for other causes of mitral valve insufficiency using the sametechniques. This is largely due to the fact that a remodelingannuloplasty with currently available rings corrects only one anomaly,and various other functional anomalies seen in ischemic mitral valveinsufficiency may not be corrected as effectively.

Annuloplasty rings have been developed in various shapes andconfigurations over the years to correct mitral regurgitation and otherconditions that reduce the functioning of the valve. For example,Carpentier, et al. in U.S. Pat. No. 4,055,861 disclosed two semi-rigidsupports for heart valves, one of which being closed (or D-shaped) andthe other being open (or C-shaped). In the closed configuration, thering is generally symmetric about an anterior-posterior plane, and has aconvex posterior side and a generally straight anterior side. U.S. Pat.Nos. 5,104,407, 5,201,880, and 5,607,471 all disclose closedannuloplasty rings that are bowed slightly upward on their anteriorside. Because the anterior aspect of the mitral annulus MA is fibrousand thus relatively inflexible (at least in comparison to the posterioraspect), the upward curve in the anterior side of each ring conformsthat ring more closely to the anatomical contour of the mitral annulus.This three dimensional configuration reduces undue deformation of theannulus.

In general, conventional annuloplasty rings are intended to restore theoriginal configuration of the mitral annulus MA. When correcting acondition as seen in FIG. 2, high stresses are created in the suturesconnecting the annuloplasty ring to posterior aspect of the annulusbecause the “overcorrecting ring,” i.e., a ring 1 to 2 sizes smallerthan the normal size “pulls” the annulus inward and upward. The stressessometimes result in the dehiscence or separation of the ring from theannulus because the sutures pull through the tissue.

It should be noted here that correction of the aortic annulus requires amuch different ring then with a mitral annulus. For example, U.S. Pat.Nos. 5,258,021 and 6,231,602 disclose sinusoidal or so-called“scalloped” annuloplasty rings that follow the up-and-down shape of thethree cusp aortic annulus. Such rings would not be suitable forcorrecting a mitral valve deficiency.

While good results in the treatment of mitral valve insufficiency,congestive heart failure, and mitral regurgitation have been obtained inthe preliminary applications of the above-described methods andapparatuses, it is believed that these results can be significantlyimproved. Specifically, it would be desirable to produce a mitralannuloplasty ring that takes into consideration all of the dysfunctionsthat exist in ischemic mitral valve insufficiency, namely, thedilatation of the annulus, the asymmetrical deformation of the annulus,and the increased distance between the posterior papillary muscle andthe annulus.

SUMMARY OF THE INVENTION

The inventors have noticed that in certain pathological conditions,there is a need to modify the minor axis/major axis size ratio in orderto make the operation of reconstruction of the mitral valve moreeffective: for instance in order to bring the valve leaflets closer toeach other in the case of anatomical or functional tissue deficiency ofone or both leaflets. It has also been observed that anatomicalvariations that do not correspond to the conventionally accepted ratioof 3:4 are frequent in nature.

According to present the invention, better mitral annulus repair resultshave been attained by means of an annular prosthesis made up of aposterior half-ring and an anterior half-ring that are coupled to eachother on a first transverse plane which defines a maximum width sectionof the prosthesis, characterized in that the ratio between the distancebetween said anterior half-ring and said posterior half-ring, asmeasured along a second plane, perpendicular to said first plane andequidistant to said couplings, and said maximum width of the prosthesisis lower than 3:4.

In one aspect, the present invention provides an annuloplasty ring forimplantation in a mitral valve annulus that has a pathologic conditionsuch that the posterior aspect thereof droops downward abnormally. Theannuloplasty ring includes a rounded ring body having an anteriorsection and a posterior section. The ring body is oriented about acentral flow axis that defines an upward direction and a downwarddirection, the downward direction corresponding to the direction ofblood flow through the mitral valve annulus. The posterior section thering body bows downward out of a plane perpendicular to the central flowaxis.

The ring body may bow downward between about 2-15 mm from one endthereof to a lowest point, and desirably bows downward between about 4-8mm from one end thereof to a lowest point. The bow in the ring body mayor may not be centered in the posterior section, and in certain cases ofischemic mitral valve insufficiency is centered in the P3 segment of thering. Preferably, the ring body is made of a malleable material suchthat the bow in the ring body may be manually reshaped. Desirably, thering body is made of a semi-rigid material that will retain itsposterior bow in opposition to the stresses that will be imparted bymuscles of the heart throughout each beating cycle. The ring body may besubstantially planar except in the posterior section, or an anteriorsection of the ring body may bow upward from one end thereof to a lowestpoint.

In plan view, as seen along the flow axis, the ring body preferablydefines an oval shape with a major axis perpendicular to a minor axis,the minor axis bisecting both the anterior and posterior sections.Further, the bow in the posterior section may begin at symmetriclocations across the minor axis that are spaced from the major axisaround the ring body by an angle θ of between about 0-45°, morepreferably about 30°.

The ring body may further include two upward bows on either side of thedownward bow on the posterior section, and wherein the downward bow maybe between about 2-15 mm. In one embodiment, the ring body comprises aplurality of ring elements concentrically disposed. A polymer strip inbetween each ring element may be provided. Optionally, the ring elementscomprise bands that have a substantially larger height in the flow axisdimension than in the dimension perpendicular to the flow axis. Further,the ring elements may have varying heights so that the ring body is moreflexible in the posterior section than around the remainder of the ringbody.

Another aspect of the present invention is a method of repairing amitral heart valve annulus that has a posterior aspect that is depresseddownward along the blood flow axis relative to an anterior aspect. Themethod includes implanting an annuloplasty ring having an anteriorsection sized to fit the anterior aspect of the annulus and a posteriorsection sized to the posterior aspect, wherein the ring posteriorsection bows downward parallel to the central axis relative to theanterior section. The annuloplasty ring may be malleable and the surgeonadjusts the bow in the posterior section manually.

Another aspect of the invention is a method of repairing a mitral heartvalve annulus that has a posterior aspect, an anterior aspect, and ablood flow axis. The method includes inspecting the shape of the mitralannulus and selecting a three-dimensional annuloplasty ring based on theshape of the mitral annulus. The selected annuloplasty ring has ananterior section and a posterior section generally arranged around acentral axis. The central axis defines an upward direction and adownward direction, wherein the ring posterior section bows downward outof a plane perpendicular to the central axis. The method includesimplanting the annuloplasty ring so that the ring posterior sectionattaches to the posterior aspect of the mitral valve annulus and theposterior section bows in the blood flow direction.

In a still further aspect, the present invention provides anannuloplasty ring for implantation in a mitral valve annulus thatincludes a rounded ring body having an anterior section and a posteriorsection. The ring body is oriented about a central flow axis thatdefines an upward direction and a downward direction, the downwarddirection corresponding to the direction of blood flow through themitral valve annulus. The shape and dimension of the ring differs fromthe shape and dimension of the currently available rings in order tocorrect the three causes of valve dysfunction described above: 1) theventricular diameter is reduced, 2) the ring is asymmetrical with inwardadvancement of the PC-P3 region creating a decrease in the obliquedistance from there to the anterior side, and 3) the P2 and P3 regionsof the ring are deflected downward in order to reduce the increaseddistance h′ between the annulus and the posterior papillary muscle.

In accordance with one particular aspect of the invention, anannuloplasty ring for implantation in a mitral valve annulus is providedthat is designed to correct ischemic mitral valve insufficiency. Theannuloplasty ring comprises a generally oval shaped ring body orientedabout a central flow axis that defines an upward direction and adownward direction. The downward direction corresponds to the directionof blood flow through the mitral valve annulus from the left atrium tothe left ventricle. In plan view, as seen along the flow axis, the ringbody has a major axis perpendicular to a minor axis, the major and minoraxes being perpendicular to the flow axis. In atrial plan view the ringbody has an anterior section generally defined between an anterolateraltrigone and a posteromedial trigone, and a posterior section around theremaining periphery of the ring body and between trigones. The posteriorsection is divided into three sequential segments, P1, P2, and P3,starting from the anterolateral trigone and continuing in acounterclockwise direction, wherein the minor axis intersects both theanterior section and the P2 segment of the posterior section.

In one version of the ring designed to correct ischemic mitral valveinsufficiency, given a predetermined major axis dimension, the ratio ofthe minor axis dimension to the major axis dimension is less than 3:4 byreducing the absolute value of the minor axis dimension by between about2-4 mm from an exact 3:4 ratio so as to restore the coaptation betweenthe two leaflets without reducing excessively the overall orifice areaof the annuloplasty ring.

In another version of the ring designed to correct ischemic mitral valveinsufficiency, the ring body lies substantially in a plane defined bythe major and minor axes or in a saddle-shaped three-dimensional surfaceexcept for a portion of the posterior section located within the P2 andP3 segments which is deflected downward with respect to the remainingsections of the ring body. The downwardly deflected portion includes anapex which is the lowest elevation of the ring body, and wherein theapex is off-center in the downwardly deflected portion toward the P1segment of the ring body. As a result, in a posterior elevational view,a transition of the ring body between the P1 segment and the apexextends along a shorter distance around the ring body than a transitionof the ring body between the apex and the non-downwardly-deflectedportion of the P3 segment.

Any of the annuloplasty rings of the present invention may furtherinclude a sewing cuff around the ring body having an enlarged portionaround the periphery of the ring body that can accommodate two radiallyadjacent rows of suture lines. Markings are desirably provided on thesewing cuff to indicate placement of the two radially adjacent rows ofsuture lines. The enlarged portion of the sewing cuff may extend aroundless than the entire periphery of the ring, and is preferably at leastpartly in the P3 segment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section of a healthy left ventricle through the mitralvalve between the anterior and posterior leaflets;

FIG. 2 is a cross-section of a dilated left ventricle through the mitralvalve between the anterior and posterior leaflets;

FIGS. 3 a-3 c illustrate normal and abnormal mitral valves from the leftatrium as exposed during surgery, that is, in atrial plan view;

FIG. 4 shows an annular prosthesis for the mitral valve according to theknown art;

FIG. 5 shows a first embodiment of an annular prosthesis for the mitralvalve according to the present invention;

FIG. 6 shows a second embodiment of an annular prosthesis for the mitralvalve according to the present invention;

FIG. 7 shows a third embodiment of an annular prosthesis for the mitralvalve according to the present invention;

FIG. 8 is a plan view of annuloplasty ring of the present inventionimplanted so as to restore competency to the mitral valve;

FIG. 9 is a perspective view of an annuloplasty ring of the presentinvention over an abnormal mitral valve as viewed from the posteriorside;

FIG. 10 is a perspective view of the annuloplasty ring of FIG. 9 overthe abnormal mitral valve as seen from the side;

FIGS. 11A-11C are plan, front, and side views of an exemplaryannuloplasty ring of the present invention having a posterior bow;

FIGS. 12A-12C are plan, front, and side views of an alternativeannuloplasty ring of the present invention having a posterior bowbetween two raised portions;

FIGS. 13A and 13B are front and side elevational views, respectively, ofan inner ring body of a further annuloplasty ring of the presentinvention having an off-center posterior bow and an anterior bow;

FIG. 14 is a top plan view of an inner ring body of an annuloplasty ringof the present invention showing details of a composite bandconstruction;

FIGS. 15A and 15B are atrial plan and posterior elevational views,respectively, of a generally planar exemplary annuloplasty ring of thepresent invention having an asymmetric configuration about a minor axisso as to have a reduced anterior-posterior dimension;

FIGS. 16A, 16B, and 16C are atrial plan, posterior elevational, andmedial elevational views, respectively, of a further exemplaryannuloplasty ring of the present invention having a downwardly deflectedposterior portion;

FIGS. 17A and 17B are posterior elevational and medial elevationalviews, respectively, of a saddle-shaped annuloplasty ring of the presentinvention having a downwardly deflected posterior portion;

FIGS. 18A-18G are atrial plan views of a series of dimensionallyaccurate prototypical annuloplasty rings of the present invention sizedfor different patients;

FIGS. 19A and 19B are atrial plan and sectional views of an annuloplastyring of the present invention showing a standard sewing cuff;

FIGS. 20A and 20B are atrial plan and sectional views of an annuloplastyring of the present invention showing a modified sewing cuff radiallyenlarged around the entire ring periphery; and

FIGS. 21A-21C are atrial plan and sectional views of an annuloplastyring of the present invention showing a modified sewing cuff with aradially enlarged segment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides various annuloplasty rings for correctingall the dysfunctions that exist in ischemic mitral valve insufficiency,and other pathologies not adequately corrected by prosthetic rings ofthe prior art. Various embodiments are shown and described in thepresent application with features that can be utilized independently orin combination. It should be understood, therefore, that any of thefeatures described herein can be supplemented by one or more of theother features. Indeed, a particularly useful combination is believed tobe either a reduction in the anterior-posterior dimension or a“pulled-in” P3 segment, in conjunction with a downward bow in theposterior section.

The attached figures illustrate several exemplary embodiments of theannuloplasty ring of the present invention, which can be described asbeing continuous and having an anterior section, a posterior section andright and left sides. All of the sides are generally curvilinear with nospecific demarcations to indicate abrupt transitions therebetween.Rather, smooth transitional sections between the adjacent sides providecurvilinear connections that give the ring a generally rounded (e.g.,oval) configuration.

The annuloplasty rings of the present invention are described asgenerally having an oval shape. This definition is intended to encompassvarious shapes in atrial plan view that are continuous around aperiphery and are longer in one dimension (along a major axis) than in aperpendicular direction (along a minor axis). As seen from the figures,the shapes are not precisely ovals but are more similar to a capital“D”, or can be likened to a kidney bean. It should also be understoodthat the various shapes are intended to conform to the native mitralannulus, but also take into consideration the various deformations anddysfunctions of the ischemic mitral valve.

In a typical mitral annuloplasty remodeling, an annuloplasty ring sizedslightly smaller than the distended annulus is implanted. The ring canbe downsized one or two sizes, which typically corresponds to areduction in the major axis dimension of 2 to 4 mm. The annuloplastyrings of the present invention incorporate this reduction by having a 2to 4 mm reduction of the minor axis dimension as compared to thecurrently available rings. Desirably, given a predetermined major axisdimension, the ratio of the minor axis dimension to the major axisdimension is less than 3:4 by reducing the absolute value of the minoraxis dimension by between about 2-4 mm from an exact 3:4 ratio so as torestore the coaptation between the two leaflets without reducingexcessively the overall orifice area of the annuloplasty ring.

Furthermore, the anterior-posterior or minor axis size reduction may bemore pronounced in the P3 region so as to further overcorrect thepredominant tethering of the posterior leaflet and the dilatation of theannulus in this region. This results in an asymmetrical shape of thering. It has been discovered that a size reduction along the minor axiseffected by reshaping the posterior section of the ring results in moresuccessful leaflet coaptation and generally better clinical results.This configuration differs from some earlier annuloplasty rings thatreduced the minor axis dimension by only reshaping the anterior sectionof the ring.

In some embodiments, the posterior section bows downward in thedirection of blood flow to help remodel the mitral annulus in the regionof the posterior leaflet scallops P2 and P3 (see FIG. 3 b) closer towardthe left ventricle LV. With such a configuration the annulus isdisplaced downward in these segments in order to reduce the distancebetween the annulus and the papillary muscle and therefore to reduce thestress on the annular sutures.

In FIG. 4 a prosthesis for annular mitral valve according to the priorart is shown. It has a kidney-like or D-shape, and it is made up of ananterior half-ring 1 rectilinear in first approximation, that is suturedin correspondence of the joining of the anterior valve leaflet 2 and acurved posterior half-ring that is sutured in correspondence of thejoining of the posterior valve leaflet. The posterior half-ring 2 andanterior half-ring 1 are coupled at two points 5 and 6 located on atransverse plane 3 that define a maximum width section of theprosthesis. In addition a longitudinal plane 4 is also defined, thatintersects the prosthesis at the points 7 and 8, which is arrangedperpendicular to the transverse plane 3 and equidistant from thecoupling points 5 and 6. The posterior half-ring 2 is thus subdivided ina first lateral zone (left) 9 located between the points 5 and 7, and asecond lateral zone (right) 10 located between the points 6 and 7. Theintersection points 5, 6 and 7, 8 of the prosthesis respectively withthe planes 3 and 4 define the terms for the calculation of thedimensions of the prosthesis. According to the known art, the ratiobetween the distance between the points 7 and 8, herein also defined asthe height of the prosthesis, and the distance between the points 5 and6, herein also defined as the width of the prosthesis, is typicallyequal to 3:4.

In FIG. 5 a first embodiment of an annular prosthesis for mitral valveaccording to the present invention is shown. It substantially has thesame shape as the one rendered in FIG. 4 but the ratio between theheight and the width of the prosthesis is lower than 3:4, for instanceequal to 2.5:4 or equal to 2:4.

For every size of prosthesis two or more reduced ratios can therefore beprovided. By “size” the dimension of the transverse width of theprosthesis is meant; the “size” represents the clinical parameter on thebasis of which the prosthesis is selected in each single clinical casein examination, and it is also the identifying parameter for theprosthesis.

The lower ratio as compared with the prostheses currently used forannuloplasty surgery allows its use in selected cases of pathologiesthat are not treatable in adequate way with conventional prostheses.

The lower ratios in this case have the function to treat pathologiescharacterized by reduced movement of the leaflets with tethering(stretching towards the cardiac apex) symmetrical (as regards eachleaflet) with medium or serious proportions. The reduction of the ratioconfers the prosthesis a more “squeezed” shape that allows a betterapposition of the leaflets in selected cases. For instance, in thedilated cardiomyopathy, when the expansion of the left ventricledetermines a lateral movement and toward the apex of the papillarymuscles, the leaflets stretch toward the cardiac apex and the appositionis thus lacking at central level. A possible sizing, in addition, mustrespect an anatomical requirement: the anterior half-ring 1 (the basefor the implant of the front leaflet) is anatomically fixed and notmodifiable, and therefore, the sizing should not be applied to thisstructure, that is to the width of the prosthesis. The maintaining of anormal fore width of the prosthesis, associated with the reduction ofthe height allows an undersizing that is less inclined to deformation ofthe fore leaflet, therefore reducing the risk of residual insufficiency.

In FIG. 6 a second embodiment of an annular prosthesis for mitral valveaccording to the present invention is shown. In this case the naturalratio height/width of 3:4 is maintained in order to define the curvingradii of the two lateral parts of the anterior half-ring. In the centralzone, in proximity of the point 7, the distance between the posteriorhalf-ring 1 and the front half-ring 2 is reduced, with the aim ofobtaining a height/width ratio lower than 3:4. The central zone of theposterior half-ring 2 therefore takes a configuration that recalls thedog bone or gull wing shape and increases the coaptation at centrallevel by limiting the annular reduction at level of the commissure.

In some extreme cases, it could be useful to make the distance betweenthe two half-rings in the central zone equal to zero, in order to obtainan eight-shape configuration, in order to improve the coaptation atcentral level. This remodeling simulates the double orifice operation,in which the leaflets are joined at the center of the valve in order toforce the central coaptation. This prosthesis could also be used withthis type of technique in order to reduce the stress on the suture andin order to minimize the reduction of the valve area.

In FIG. 7 a third embodiment of an annular prosthesis for mitral valveaccording to the present invention is shown. In this embodiment thecurving radius of one of the lateral zones, for instance the secondlateral zone (right) 10, is increased so as to induce a selectiveincrease of the competence in correspondence of the valve sector withreduced mobility of the leaflets (bad asymmetric apposition of theleaflets as in ischemic pathology). It is thus obtained that one part ofthe prosthesis, for instance the first lateral zone (left) 9, maintainsa configuration substantially similar to the traditional prosthesis andone part, for instance the second lateral zone (right) 10, gets a sizedconfiguration. In other words the distance between the middle point ofthe first lateral zone (left) 9 and the longitudinal plane 4 is greaterthan the distance between the middle point of the second lateral zone(right) 10 and the longitudinal plane.

The prosthesis, according to the present invention, can be made of aninert material that is highly tolerated by the human organism and canhave a resistance that is appropriate to the use and that cansubstantially maintain the shape given to it.

An exemplary annuloplasty ring 30 of the present invention is shown inFIG. 8 implanted around a mitral annulus MA. As described above, themitral annulus has an anterior leaflet AL and a posterior leaflet PL.When the ring 30 is implanted, the leaflets are brought closer togetherand supported so that they meet at a coaptation surface 32. The ring 30thus corrects the problem of functional mitral regurgitation.

The ring 30 has an oval or somewhat D-shaped configuration with arelatively straight anterior section 34 opposite a curved posteriorsection 36. A pair of trigone or commissure markers 38 a, 38 b generallydelimit the anterior side 34, while a pair of opposed side sections 40a, 40 b extend between each of these markers and the posterior section36. A plurality of knotted suture loops 42 are typically used to securethe ring 30 to the mitral annulus MA, although other fasteners such asstaples, fibrin glue, or the like may be used.

In the pathological conditions for which the annuloplasty ring 30 isbest suited, the posterior aspect of the mitral annulus is depressedrelative to the anterior aspect, as is illustrated in FIG. 2. In theview of FIG. 8, the posterior aspect will be depressed into the pagerelative to the anterior aspect. The annuloplasty ring 30 of the presentinvention has a shaped posterior section 36 that generally follows themodified shape of the mitral annulus MA. In other words, the posteriorsection 36 is bowed into the page relative to the anterior section 34.When secured in place with sutures 42, for example, the ring 30 supportsthe mitral annulus MA in its modified shape, rather than trying torevert the annulus back to the original substantially planarconfiguration. At the same time, the ring 30 desirably constricts theorifice circumference defined by the annulus so as to bring the anteriorleaflet AL and posterior leaflet PL closer together. Because the ring 30does not pull the posterior aspect of the mitral annulus MA upward fromits modified position, high stresses are not set up in the attachmentsutures 42 and thus there is less potential for the dehiscence.

FIGS. 9 and 10 illustrate the exemplary annuloplasty ring 30 inperspective above a mitral annulus that is depressed on its posteriorside. The bow of the ring 30 in its posterior section 36 is seen best inFIG. 10 mimicking the depression of the posterior aspect of the mitralannulus MA in the pathology encountered with functional mitralregurgitation.

The exemplary annuloplasty ring 30 of FIGS. 8-10 is shown in more detailin FIGS. 11A-11C. The ring 30 is shown complete with a fabric covering.For purpose of orientation, FIG. 11A illustrates orthogonal axes whereinthe X- and Y-axes generally define the datum plane 20 as mentioned abovewith respect to FIGS. 1 and 2. The X-axis extends across the ring 30from one side 40 a to the opposite side 40 b at the point of maximumdimension. The X-axis thus defines a major axis of the ring 30. TheY-axis defines a plane of symmetry for the ring 30 extending between amidpoint of the anterior side 34 to a midpoint of the posterior section36. The Y-axis also defines a minor axis for the ring 30.

As with many conventional rings, the ratio of the minor axis dimensionto the major axis dimension is desirably about 3:4. This size ratio isthe “classic” shape of the mitral annulus, and may be the bestconfiguration of the annuloplasty ring 30. However, it is contemplatedthat other shapes that have smaller minor axis-to-major axis ratios mayactually increase leaflet coaptation. Although not geometricallyprecise, the non-circular ring configuration may be considered oval,elliptical or D-shaped. It should be noted that the present inventioncould also take the form of a discontinuous ring that has a C-shape, forexample. The break in such a ring may be in the anterior section, andthe posterior section is continuous and exhibits the downward bow asexplained.

The Z-axis in FIG. 11B lies along of the axis of blood flow through thering 30 when implanted, and it will be understood that the positive Zdirection is the “upward” direction, the negative Z direction is the“downward” direction, and the ring 30 is designed to be implanted in amitral annulus such that blood will flow in the downward direction.

Several points are noted around the ring 30 to help describe theposterior bow. These points, and the ones shown in FIGS. 12A-12B, areimaginary center points through the cross-section of the ring 30. Twopoints A are symmetrically located on either side of the Y-axis at anangular distance θ from the X-axis. The midpoint of the posteriorsection 36 is denoted B. The ring 30 has a posterior bow such that thepoint B is at the lowest elevation along the Z-axis. The magnitude ofthis posterior bow is indicated by the dimension Z₁ in FIG. 11C. Thepoints A on either side of the posterior section 36 represent thelocation where the posterior bow begins. That is, except for theposterior section, the ring 30 is preferably substantially planar.However, the anterior section 34 can optionally be bowed upward by adistance of between about 2-4 mm (0.08-0.16 inches), as in certain ringsof the prior art. In the latter example, the posterior section 36 bowsdownward in the Z-direction relative to the elevation of the trigonemarkers 38 a, 38 b.

Various possible configurations for the ring 30 as seen in FIGS. 11A-11Care contemplated, with the dimension Z₁ and the angle θ varying betweenranges determined by the overall size of the mitral annulus, the extentof anatomical droop of the posterior aspect, and various other factorsincluding surgeon preference. Nevertheless, certain ranges are believedsuitable to support and correct a majority of the patients exhibitingthe particular anatomical irregularity as described herein. The downwardbow or posterior bow preferably extends along a majority of theposterior section 36 between the points A, which points are between 0and 45° from the X-axis (θ). More preferably, the points A are between20-40°, and more particularly about 30° from the X-axis. The magnitudeof bow Z₁ may be between about 2-15 mm (0.08-0.59 inches), and moretypically is between about 4-8 mm (0.16-0.31 inches), depending on thesize of the ring.

Although the ring 30 is shown in FIGS. 11A-11C as symmetric about theY-axis, it does not necessarily have to be so. For example, the point Bmay be displaced from the Y-axis such that the downward bow is notcentered in the posterior section 36. An asymmetric ring is shown anddescribed below with reference to FIGS. 13A and 13B.

FIGS. 12A-12C illustrate an alternative annuloplasty ring 50 of thepresent invention that has both upward and downward bows. Again, thering 50 is shown complete with a fabric covering. The ring 50 includesan anterior section 52, a posterior section 54, and a pair of sidesections (not numbered) therebetween. The ring 50 is generally planar onthe anterior section 52 and shaped on the posterior section 54. Thepoints A symmetrically disposed across the Y-axis again denote thelocations on each side where the ring 50 begins to curve out of a plane.In this embodiment, the ring curves upward in the Z-direction from thepoints A, as best seen in FIG. 12B, to high points C, and then dipsdownward to the midpoint B of the posterior section 54. The downward bowof the ring between points A and B is shown in FIG. 12C as the dimensionZ₂, which has a magnitude similar to that given for Z₁ in FIG. 11C. Theupward curve may be selected so as to better match the patient's annulusshape. Furthermore, the anterior section 52 may be upwardly bowed by adistance of between about 2-4 mm (0.08-0.16 inches).

Various permutations of the ring 50 shown in FIGS. 12A-12C arecontemplated, with the dimensions being altered based on numerousfactors. In an exemplary embodiment, the points A are desirably disposedan angle α from the X-axis of between about 0-15°, and more desirablybetween about 5-10°. The points C of maximum height of the ring 50 arepreferably spaced an angle β from the X-axis of between about 15-45°,and more preferably between about 25-35°. The lowest point B of the ring50 may be bowed along the Z-axis as in the embodiment of FIGS. 11A-11C,so that, as indicated FIG. 12C, Z₂ is desirably between about 2-15 mm(0.08-0.59 inches), and more typically is between about 4-8 mm(0.16-0.31 inches), depending on the size of the ring. Therefore, thetotal height of the ring 50 is at least 2 mm, and may be greater than 15mm.

FIGS. 13A and 13B show an inner ring body 60 for use in an annuloplastyring of the present invention. The ring body 60 has a posterior bow 62that is offset from the center of a posterior section 64. In theillustrated embodiment, the bow 62 is offset toward the posteriomedialside (to the right) by about 20% of the entire major axis width of thering body 60. Another way to state the offset is that, in plan view, thebow 62 is centered at a clock position, with 12:00 being centered in theanterior side. In that sense, the bow 62 is centered between 3:00 and6:00, and more preferably is centered at about 5:00 (using theterminology of FIGS. 15A and 16A, the bow 62 is centered somewhere inthe posterior segments P2 and P3, but offset from the center of the P2segment). The axial magnitude of the downward bow Z₃ is shown and mayvary from about 2.0 mm (0.08 inches) to about 4.0 mm (0.16 inches), andmore preferably from about 3.0 mm (0.12 inches) to about 3.8 mm (0.15inches), depending on ring size. In addition, the ring body 60 has ananterior section 66 that is upwardly bowed by a distance of betweenabout 2-4 mm (0.08-0.16 inches).

The inner ring body 60 demonstrates an asymmetric ring that conforms topatients that have a posterior annular bow that is displaced from themidline. It is believed that most patients have such a malformed anatomyresulting from the pathologic conditions described herein. However,posterior bows that are centered or even offset to the left have beenobserved. Therefore, one configuration of ring that is embodied in thepresent invention is one that is pre-shaped with a posterior bow in themiddle or to the right, and that is malleable so that the bow can beexaggerated or diminished by the surgeon after examination of theprecise shape of the patient's annulus. Further, in such a convertiblering the bow can even be displaced, from the right to the left, forexample. Although the material of the ring permits manual deformation,it would be stiff enough to withstand further deformation once implantedand subjected to normal physiologic stresses.

The ring preferably includes an inner ring body and an outer sewingsheath that permits the ring body to be sutured into the mitral annulus.The sewing sheath should be sufficiently porous and/or flexible topermit sutures to be passed therethrough. One exemplary construction isto enclose the inner ring body in a tubular sheath of suture-permeablematerial, such as silicone, which is then covered with a fabric tube,such as polyethyl terepthalate. As opposed to flexible annuloplastyrings that are designed simply to reduce the circumference of the mitralannulus, the annuloplasty ring of the present invention must besemi-rigid. It must retain its posterior bow in opposition to thestresses that will be imparted by muscles of the heart throughout eachbeating cycle. For example, the ring body may be made from materialssuch as Elgiloy (a cobalt-nickel alloy), titanium, or Nitinol (anickel-titanium alloy). Exemplary ring constructions are seen in theCARPENTIER-EDWARDS CLASSIC® Annuloplasty Ring, and in theCARPENTIER-EDWARDS PHYSIO® Annuloplasty Ring, both made and sold byEdwards Lifesciences of Irvine, Calif.

FIG. 14 illustrates one exemplary construction of the inner body of theannuloplasty rings of the present invention that utilizes multiple flatbands of Elgiloy in a composite structure. Specifically, there are fourbands 70 a, 70 b, 70 c, and 70 d from the outside to the inside. Thefour bands are concentrically disposed in the shape of the ring. Eachband is a flat strip of material having a width of between about 1.4-2.0mm (0.056-0.078 inches). In one embodiment, the bands 70 overlap in theanterior section 72 of the ring body and are fastened together by, forexample, spot welding at multiple points. The width of each strip mayalso be greater in the anterior section 72 than in a posterior section74, which means that the ring body is more flexible in the posteriorsection than in any other section. Although not shown, a plurality ofstrips of protective film is used in between each band 70, and on theouter face of the outer band 70 a. The strips may be a polymer such asMylar. The strips help reduce rubbing between the bands 70 and alsodeflect suture needles from the outer band 70 a and thus preventscratching thereto.

It will also be readily apparent that supporting the mitral valveannulus with the present annuloplasty ring will maintain the posteriorleaflet depressed below the anterior leaflet, and thus the area ofcoaptation therebetween will be different than in a healthy valve. Thisis required by the pathology of the ventricle with displacement of thepapillary muscles and posterior leaflet. However, those of skill in theart will recognize that this slight realignment of the leaflets isacceptable because of the surplus area of the leaflets available forcoaptation, and because the realignment will be offset by other changesto the shape of the annulus that should over time improve coaptation ofthe two leaflets and therefore decrease regurgitation.

A further exemplary embodiment of an annuloplasty ring 130 of thepresent invention is seen in FIGS. 15A and 15B. FIG. 15A is a so-calledatrial plan view because it visualizes the ring 130 along a flow axis132 from the atrial side. That is, blood flow will be into the pagethrough the ring 130 as seen in FIG. 15A, and downward in FIG. 15B.

The annuloplasty ring 130 is shown fully constructed with an externalfabric covering (not numbered) over an internal ring body. It will beunderstood that the flexible fabric covering adds relatively little tothe overall shape of the ring 130, and therefore the configurationdepends on the shape of the internal ring body. Therefore, when thevarious shapes of the rings herein are described it is really the shapesof the ring bodies that are referenced.

The annuloplasty ring 130 comprises an anterior section AS definedbetween an anterolateral trigone T1 and posteriomedial trigone T2, withthe remainder of the ring defined between the trigones by a posteriorsection made up of three sequential segments: P1, P2, and P3. Theannuloplasty ring 130 is generally oval-shaped with a longer dimensionalong a major axis 134, a shorter dimension along a minor axis 136. Theminor axis 136 intersects both the anterior section AS and the posteriorsegment P2. In a preferred embodiment, the minor axis 136 bisects boththe anterior section AS and the posterior segment P2.

As seen in FIG. 15B, the annuloplasty ring 130 lies substantially in theplane defined by the major and minor axes 134, 136, which plane isdesirably perpendicular to the flow axis 132. In an alternativeembodiment, the anterior section AS may be deflected upward (withrespect to the flow axis 132) as seen by the dashed line indicated asAS′. This upwardly deflected anterior section AS' provides a desirablethree dimensional configuration which conforms to the upwardly bowedanterior aspect of the mitral annulus.

With reference again to FIG. 15A, four radial lines 140 a, 140 b, 140 c,140 d emanate outward from the flow axis 132 to indicate the dividinglines between the anterior section AS and the posterior segments P1, P2,and P3. The anterior section AS can be fairly accurately located betweenthe trigones T1 and T2, which are typically marker threads thatcorrespond to the positions of the native trigones or commissures suchas seen in FIG. 3 a. On the other hand, the posterior segments P1, P2,and P3 are shown somewhat schematically as circumscribing particulararcs around the periphery of the posterior section. The magnitude of thearcs defined by the posterior segments P1, P2, and P3 may vary dependingon a variety of factors, including actual measurement of the mitralvalve posterior leaflet scallops, and surgeon preference. As a rule,however, the major axis 134 intersects both the first and secondposterior segments P1 and P3, and the minor axis 136 intersects themiddle posterior segment P2.

The annuloplasty ring 130 has an asymmetric configuration across theminor axis 136 with the convexity of the P1 segment of the posteriorsection being greater than the convexity of the P3 segment. Inparticular, a portion of the P3 side is pulled in toward the center ofthe ring so as to define an oblique inner dimension line 142 a that isshorter than an oblique inner dimension line 142 b. The dimension lines142 a, 142 b are measured from a point 144 on the minor axis 136 on themiddle inner edge of the anterior section AS. The dimension line 142 ais drawn to the point in the P3 zone that is closest to the point 144 atthe middle of the anterior section AS, and forms an angle θ with theminor axis 136. The dimension line 142 b is also oriented at an angle θfrom the minor axis 136 but in the opposite rotational direction formthe line 142 a.

Stated another way, the annuloplasty ring 130 has a generally oval shapeexcept for a reduced curvature portion 150 extending between a point 152at the intersection of the minor axis 136 and the posterior segment P2,and the second trigone T2. “Reduced curvature” is relative to thecurvature of the opposite side of the ring 130 across the minor axis136; namely, relative to the segment P1 and the left side of segment P2.The conventional “oval” shape of the ring 130 is illustrated by a dashedline extension 154 around the modified portion of the ring, and thedivergence of the reduced curvature portion 150 is apparent. The reducedcurvature portion 150 is shown extending through approximately half ofthe central posterior segment P2 and all of the third posterior segmentP3. Alternatively, the central posterior segment P2 could continue theoval shape of the remainder of the ring 130 and the reduced curvatureportion 150 could extend only from imaginary point 156 to the secondtrigone T2. The reduced curvature portion 150 is desirably less convexthan the imaginary oval shape 154, but may even be linear, or evenslightly concave.

The effect of providing the reduced curvature portion 150 of the P3segment, is to remodel the mitral annulus in the region of the posteriorleaflet scallop P3 (see FIG. 3 b) closer toward the flow axis than theother scallops. The reduction of the anterior-posterior dimension of themitral annulus in this manner is believed to more effectively correctfor dysfunctions that exist in ischemic mitral valve insufficiency.

FIGS. 16A-16C are plan and elevational views of an alternativeannuloplasty ring 160 of the present invention also configured tocorrect for all dysfunctions that exist in ischemic mitral valveinsufficiency. As with the earlier described ring 130, the annuloplastyring 160 is generally oval shaped around a flow axis 162, and withrespect to a major axis 164 and a minor axis 166. The ring 160 has ananterior section AS defined between two trigones T1 and T2, and aposterior section extending around the remainder of the ring between thetrigones and composed of three sequential segments: P1, P2, and P3.

The annuloplasty ring 160 lies substantially in a plane (or in asaddle-shaped three-dimensional surface) except for a portion 170 of theposterior section located within the P2 and P3 segments that isdeflected downward with respect to the flow axis 162. As seen best inFIG. 16B, the downwardly deflected portion 170 includes an apex A whichis the lowest elevation of the ring 160. The downwardly deflectedportion 170 is desirably exclusively within the P2 and P3 segments andis shown to extend from point B to point C around posterior section.Point B desirably lies at the intersection between the first and secondposterior segments P1 and P2, while point C desirably lies at theintersection of the major axis 164 and the third posterior segment P3.The exact location of points A, B, and C may vary as long as thedeflected portion 170 exists in the posterior section of the ring 160and primarily outside of the first posterior segment P1.

In preferred embodiment, the apex A of the deflected portion 170 isoff-center toward the P1 segment such that, as seen in FIG. 16B, atransition 172 between points A and B extends along a shorter distancearound the ring 160 than a transition 174 between points A and C. Morepreferably, the transition 174 between points A and C is almost linearas shown. The effect of providing the downwardly deflected portion 170and elongated transition 174 is to remodel the mitral annulus in theregion of the posterior leaflet scallops P2 and P3 (see FIG. 3 b) closertoward the left ventricle LV so as to displace downward the annulus inthese segments in order to reduce the increased distance h′ between theannulus and the papillary muscle and to reduce the stress on the annularsutures.

The anterior section AS is shown in FIG. 16A as being linear, but analternative configuration is shown in dashed line at AS′. Thealternative anterior section AS' is deflected slightly inward along theminor axis 166 and thus reduces the anterior-posterior dimension of thering 160. As mentioned above, the reduced curvature portion 150 of thering 130 in FIG. 15A can also be combined with the downwardly deflectedportion 170 to further reduce the anterior-posterior dimension.

A further exemplary embodiment of an annuloplasty ring 180 of thepresent invention is seen in FIGS. 17A in 17B. The nomenclature usedabove with respect to the sections and segments around the ring areconsistent. The ring 180 is similar in many respects to the ring 160seen in FIGS. 16A-16C in that incorporates a downwardly deflectedportion 182 in the posterior section. Again, the deflected portion 182has an apex A which is off-center with respect to the minor axis (notshown) of the ring 180 toward the P1 segment of the posterior section.

The annuloplasty ring 180 is substantially saddle-shaped as opposed tobeing substantially planar. That is, the posterior segments P1 and P3rise upward from a reference plane 184 while the anterior section ASlies generally on the reference plane. If the ring 180 were completelysaddle-shaped, the central posterior segment P2 would also lie on thereference point. Instead, the downwardly deflected portion 182 bringsthe posterior segment P2 below the reference plane 184. It should beunderstood, therefore, that the portion 182 deflects downward from thesaddle-shaped remainder of the ring 180.

In a preferred construction, the annuloplasty ring bodies of the severalrings of the present invention are constructed to be more flexible inthe posterior section than in the anterior section AS. For example, thering body may be constructed with a metallic core of different thicknessor with a series of annular bands that overlap in the anterior sectionto render that section less flexible than in the posterior section. Inan alternative construction the ring is completely rigid throughout.

FIGS. 18A-18G illustrate a series of annuloplasty rings 200 a-200 g ofthe present invention that are sized for different patients. Thedrawings are dimensionally accurate for a series of prototypes that areshown in atrial plan view. Each ring can be made in one plane or canhave a saddle shape, such as the annuloplasty ring 180 of FIGS. 17A-17B.That is, the posterior segments P1 and P3 (noted only in FIG. 18F) mayrise upward with respect to the posterior segment P2 and anteriorsection AS.

The major axis 202 and minor axis 204 are shown for ring 200 b in FIG.18B, and the same orientation applies to each ring 200 a-200 g. Thedimension x_(i) along the major axis 202 and dimensions y_(i) along theminor axis 204 are denoted for each ring 200 a through 200 g. Thefollowing table provides these dimensions, as well as the labeled ringsize that would be used for selecting a specific ring. That is, a Size34 ring is the label for a ring destined to be implanted in a patienthaving a measured native annulus, or surgeon-determined annulus, ofabout 34 mm along the major axis. These dimensions are measured perconvention between the inner surfaces of each ring along the respectiveaxes.

TABLE I Dimensions of Annuloplasty Rings of FIGS. 18A-18G Ring MajorAxis, Minor Axis, Ratio of Ring Size x_(i) (in./mm) y_(i) (in./mm)y_(i)/x_(i) (%) 200a 24 0.885/22.5 0.534/13.6 60.3 200b 26 0.961/24.40.580/14.7 60.3 200c 28 1.036/26.3 0.626/15.9 60.4 200d 30 1.112/28.20.672/17.1 60.4 200e 32 1.187/30.1 0.719/18.3 60.6 200f 34 1.263/32.10.765/19.4 60.6 200g 36 1.338/34.0 0.811/20.6 60.6

As mentioned above, the minor axis dimensions y_(i) are reduced for eachring such that the ratio of the minor axis dimension to the major axisdimension is less than 3:4 (or less than 75%). In absolute terms, thisis a reduction of between about 2-4 mm from an exact 3:4 ratio so as torestore the coaptation between the two leaflets without reducingexcessively the overall orifice area of the annuloplasty ring. Forexample, Size 24 ring 200 a of FIG. 18A has a major axis dimension x_(a)of 0.885 in. (22.5 mm). A precise 3:4 minor/major axis ratio wouldresult in a minor axis dimension of 0.664 in. (16.9 mm). However, theminor axis dimension y_(a) is 0.534 in. (13.6 mm), a reduction from theexact 3:4 ratio of about 3.3 mm.

Viewed another way, each ring 200 a-200 g has a minor axis dimensionreduction of about 14% from the conventional or normal ring size. Thisis approximately equivalent to a reduction of about one ring size (e.g.,a Size 26 ring to a Size 24 ring is one ring size reduction). However,the use of the rings of the present invention is not the same as thecurrent “downsizing” practice because the ring that is ultimately usedis not labeled as a smaller sized ring. For instance, current practicemay be to “downsize” and use a Size 24 ring for a measured Size 26patient. Ring 200 b of FIG. 18B would be the selected ring in accordancewith the present invention for a Size 26 patient. Ring 200 b is labeledas a Size 26 ring, although it is downsized in dimension from theconventional ring size. Therefore, there is no uncertainty about whichring to select—a size 26 ring is for a Size 26 patient. Also,conventional practice leaves no “downsizing” choice for small patientswith annulus sizes of 24 mm. That is, there is typically no Size 22 ringavailable. The Size 24 ring 200 a of the present invention, on the otherhand, is already downsized, and provides the improved coaptation resultspreviously mentioned for indicated patients.

Most significantly, however, downsizing reduces the entire ringperiphery when often only a segment of the mitral annulus need becorrected. For instance, an asymmetric dilation such as seen in FIG. 3 brequires correction of only a portion of the posterior aspect, in theregion of the P2-P3 leaflet scallops. Simply implanting a smaller ringwould correct the affected region but would also constrict the healthyregions, and in particular can overly stress the more fibrous anterioraspect which typically does not change size or shape. Rings of thepresent invention account for the selective peripheral downsizingrequired due to certain pathologies such as ischemic mitralregurgitation.

It should also be noted that the dimensions along the major axes of eachring are less than the measured or otherwise determined annulus size, inkeeping with one of the aspects of the invention, which is downsizingthe entire ring, not just the anterior-posterior dimension. The desiredabsolute major axis dimension reduction is between about 1.0-1.5 mm. Forexample, the convention or normal major axis dimension for Size 24 ring200 a of FIG. 18A is about 24 mm. However, ring 200 a of FIG. 18A has anactual major axis dimension x_(a) of 0.885 in. (22.5 mm), which is areduction of about 1.5 mm, or about 6%. One of skill in the art willappreciate the difference between selecting a “downsized” ring of thesame proportional 3:4 size ratio and using the rings of the presentinvention. Namely, conventional practice of “downsizing” for a Size 26patient would dictate using a conventional Size 24 ring, with a 24 mmmajor axis and an 18 mm minor axis (a 3:4 ratio). The Size 26 ring ofthe present invention, on the other hand, has a 24.4 mm major axis and a14.7 mm minor axis (a 3:5 ratio).

All of the annuloplasty rings 200 a-200 g shown in FIGS. 18A-18G havethe asymmetry previously noted wherein the P3 segment (see FIG. 18F)corresponding to the P3 leaflet has a reduced curvature relative to theP1 segment (or, the convexity of the P1 segment is greater than that ofthe P3 segment). This asymmetry was shown and described above withrespect to the ring 130 of FIGS. 15A and 15B.

Looking at two particular examples, FIGS. 18A and 18G illustrates a Size24 ring 200 a and a Size 36 ring 200 g, respectively, that have areduced curvature, or “pulled-in”, length generally along the P3segment. The length along each ring 200 a-200 g that is pulled in isdesirably within a particular arc around the ring periphery that islocated within the P2 and P3 segments. A horizontal line 206 is drawnalong the inner surface of the anterior segment AS of the rings, andthree angles α and β are shown extending clockwise therefrom about acentral reference point 208 along the minor axis 204. The “pulled-in”length, or length of reduced convexity in comparison to the oppositeside of the ring, is located between the angles α and β. For the ring200 a of FIG. 18A, α is 23.2° and β is 90°. For the ring 200 g of FIG.18G, α is 15.8° and β is 90°. The angle β lies along the minor axis 204and intersects the posterior side of the ring. These are the outerbounds of the rings 200 a-200 g so that a ranges between 15.8-23.2°, andthe “pulled-in” length is between about 57-74° extendingcounter-clockwise from the intersection of the minor axis 204 and theposterior side of the ring.

A third angle θ is also drawn in FIGS. 18A and 18G which indicates theangle at which the distance along the “pulled-in” length of the ringperiphery and the central reference point 208 is least. That is, thepoint 210 is the closest of any point along the “pulled-in” length topoint 208, and the distance is indicated by dimension line 212. Afurther point 214 is indicated on the ring periphery but on the sideopposite point 210 across the minor axis 204 (in the P1 segment). Thepoint 214 is located at the same angle θ from the horizontal line 206about the central reference point 208 but in the counter-clockwisedirection. These lines 212, 216 are drawn along lines emanating betweenthe respective segments and the intersection of the anterior section andthe minor axis. Line 216 indicates the “normal” dimension between points208 and 214. In a preferred embodiment, the ratio of the “pulled-in”dimension 212 to the “normal” dimension 216 is about 0.89 (89%), and theangle θ is about 51°. For ring 200 a, dimension 212 is about 0.503 in.(12.8 mm) and the dimension 216 is about 0.564 in. (14.3 mm), a ratio ofabout 89%. For ring 200 g, dimension 212 is about 0.754 in. (19.2 mm)and the dimension 216 is about 0.846 in. (21.5 mm), again for a ratio ofabout 89%.

The annuloplasty rings 130, 160, 180, or 200 a-200 g are secured to thepatient's annulus using sutures placed in the annulus and then in asewing cuff which is part of the ring itself. A sewing cuff in thissense means any suture-permeable material or combination thereof that isan integral part of the ring and which is large enough to receive atleast a single row of sutures. In conventional models, the sewing cuffis about 2-5 mm wide on the outer periphery of the annuloplasty ring andaccommodates a single row of sutures.

For instance, FIGS. 19A-19B illustrate an annuloplasty ring 250 having ashape similar to that of the ring 130 of FIGS. 15A and 15B, and show asingle row suture line 252 around the periphery. The cross-section ofFIG. 19B illustrates a sewing cuff 254 and an internal structuralcomponent 256 of the ring 250 that is typically a wire or band ofstainless steel, titanium, or other suitable material.

FIGS. 20A-20B illustrate a preferred construction of an annuloplastyring 260 that is particularly suited for repair of an annulus afflictedby ischemic disease. Again, the ring 260 has a shape approximately likethat of the ring 130 of FIGS. 15A and 15B. FIG. 20B shows a sewing cuff262 on an outer periphery of the ring 260 that is radially wider thanthe cuff 254 of FIGS. 19A-19B. In an exemplary embodiment, the sewingcuff 262 has a radial dimension r of between about 5-10 mm. As seen inFIG. 19A, the larger sewing cuff 262 accommodates a double row of suturelines, as indicated by a row of markers 264 as a guide to the surgeon.This provides a more secure fixation of the ring 260 to the diseasedannulus and helps prevent dehiscence.

FIGS. 21A-21C show an alternative annuloplasty ring 270 of the presentinvention that includes a suture cuff area 272 in the P3 region that isradially enlarged in comparison to the remaining suture cuff 274. The P3region is often the most distended and fragile portion of the nativeannulus and thus the enlarged suture cuff area 272 provides a moresecure fixation of the ring 270 to the diseased annulus and helpsprevent dehiscence at that location. The majority of the suture cuff 274may be between about 2-5 mm in radial dimension while the suture cuffarea 272 is between about 5-10 mm. Of course, such a configuration withless than the whole and only a segment of the periphery of the sewingcuff being enlarged is applicable to other disease states or evensurgeon preference, and therefore the suture cuff area 272 can belocated other than in the P3 region.

It will also be appreciated by those of skill in the relevant art thatvarious modifications or changes may be made to the examples andembodiments of the invention described in this provisional application,without departing from the intended spirit and scope of the invention.In this regard, the particular embodiments of the invention describedherein are to be understood as examples of the broader inventive conceptdisclosed in this application.

What is claimed is:
 1. A method of remodelling an abnormal mitral valveannulus having a clinically measured native annulus “size” given in evenmm increments corresponding to a transverse dimension across its orificealong a transverse axis, the annulus further having ananterior-posterior dimension along an anterior-posterior axis across itsorifice perpendicular to the transverse axis, the abnormality of themitral valve annulus exhibiting primarily in dilatation of a posterioraspect of the mitral annulus and reduced valve leaflet coaptation, themethod comprising: implanting a continuous, closed generally rigid bodyaround the annulus, wherein the rigid body forms a peripheral shapeabout an opening, the opening having a major axis dimension along amajor axis perpendicular to a minor axis dimension along a minor axis,and wherein the ratio of the minor axis dimension to the major axisdimension is smaller than a ratio of the anterior-posterior dimension tothe transverse dimension of the annulus, so as to constrict the annulusmore along the anterior-posterior axis than along the transverse axis soas to constrict the dilated posterior aspect of the annulus and restorecoaptation between the valve leaflets.
 2. The method of claim 1, whereinthe ring body is “downsized” by reducing the minor axis dimension bybetween about 2-4 mm relative to the corresponding anterior-posteriordimension of the annulus.
 3. The method of claim 1, wherein the majoraxis dimension is smaller than the measured transverse dimension of theannulus.
 4. The method of claim 1, wherein the ratio of the minor axisdimension of the opening to the major axis dimension of the opening isless than 3:4.
 5. The method of claim 4, wherein the ratio of the minoraxis dimension of the opening to the major axis dimension of the openingis less than or equal to 2.5:4.
 6. The method of claim 1, wherein thering body comprises a metal.
 7. The method of claim 1, wherein the ringbody has an anterior segment opposite a posterior segment which isdivided into P1, P2, and P3 segments, with the minor axis bisecting theP2 segment, and wherein the posterior segment is asymmetric with the P3segment being located closer to the anterior segment than is the P1segment.
 8. The method of claim 7, wherein the posterior segment has adownward bow.
 9. The method of claim 7, wherein the rigid body iscovered with a sewing cuff that has an enlarged portion around theperiphery of the ring body in the P3 segment that can accommodate tworadially adjacent rows of suture lines, the method including sewing theannuloplasty ring to the annulus using the sewing cuff and securing theannuloplasty ring with two rows of suture lines at the enlarged portionof the sewing cuff.
 10. A method of remodelling an abnormal mitral valveannulus having a clinically measured native annulus “size” given in evenmm increments corresponding to a transverse dimension across its orificealong a transverse axis, the annulus further having ananterior-posterior dimension along an anterior-posterior axis across itsorifice perpendicular to the transverse axis, the abnormality of themitral valve annulus exhibiting primarily in asymmetric dilatation of aposterior aspect of the mitral annulus and reduced valve leafletcoaptation, the method comprising: implanting a continuous, closedgenerally rigid body around the annulus, wherein the rigid body forms aperipheral shape about an opening, the opening defined by the ring bodyhaving a major axis perpendicular to a minor axis, and wherein the bodyis “downsized” with the peripheral shape smaller than the measuredannulus so as to constrict the annulus when implanted, and wherein thering body is reduced in size along the minor axis relative to thecorresponding anterior-posterior dimension of the annulus a greateramount than the ring body is reduced in size along the major axisrelative to the transverse dimension of the annulus, so as to constrictthe dilated posterior aspect of the annulus and restore coaptationbetween the valve leaflets.
 11. The method of claim 10, wherein the ringbody is “downsized” by reducing the minor axis dimension by betweenabout 2-4 mm relative to the corresponding anterior-posterior dimensionof the annulus.
 12. The method of claim 10, wherein the ring body is“downsized” by reducing the major axis dimension by between about1.0-1.5 mm relative to the corresponding transverse dimension of theannulus.
 13. The method of claim 10, wherein the ratio of the minor axisdimension to the major axis dimension is less than 3:4.
 14. The methodof claim 13, wherein the ratio of the minor axis dimension to the majoraxis dimension is less than or equal to 2.5:4.
 15. The method of claim10, wherein the ring body comprises a metal.
 16. The method of claim 15,wherein the metal is titanium.
 17. The method of claim 10, wherein thering body has an anterior segment opposite a posterior segment which isdivided into P1, P2, and P3 segments, with the minor axis bisecting theP2 segment, and wherein the posterior segment is asymmetric with the P3segment being located closer to the anterior segment than is the P1segment.
 18. The method of claim 17, wherein the posterior segment has adownward bow.
 19. The method of claim 17, wherein the rigid body iscovered with a sewing cuff that has an enlarged portion around theperiphery of the ring body in the P3 segment that can accommodate tworadially adjacent rows of suture lines, the method including sewing theannuloplasty ring to the annulus using the sewing cuff and securing theannuloplasty ring with two rows of suture lines at the enlarged portionof the sewing cuff.
 20. The method of claim 19, further includingmarkings provided on the sewing cuff to indicate placement of the tworadially adjacent rows of suture lines.